A ruler stands vertically against a wall. It is given a tiny impulse at θ=0∘ such that it starts falling down under the influence of gravity. You can consider that the initial angular velocity is very small so that ω(θ=0∘)=0. The ruler has mass m= 100 g and length l= 35 cm. Use g=10 m/s2 for the gravitational acceleration, and the ruler has a uniform mass distribution. Note that there is no friction whatsoever in this problem. (See figure)
(a) What is the angular speed of the ruler ω when it is at an angle θ=30∘? (in radians/sec)
ω=
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(b) What is the force exerted by the wall on the ruler when it is at an angle θ=30∘? Express your answer as the x component Fx and the y component Fy (in Newton)
Fx=
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Fy=
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(c) At what angle θ0 will the falling ruler lose contact with the wall? (0≤θ0≤90∘; in degrees) [hint: the ruler loses contact with the wall when the force exerted by the wall on the ruler vanishes.]
θ0=
yes please.. that's the only question where I'm stuck too..
Me too!!!
Hi Teresa, can you do rocket problem me pls?
p: percentage (4.5% is burned in 155s)
m:mass of rocket
u:fuelspeed in meter/s!
v=u*ln(1/(1-p))=1500*ln(1/0.955)
a=v/t = 69.065/155= 0.4455
Hi Teresa, in my problem, question says The rocket burns 10 % of its mass in 290 s (assume the burn rate is constant).
What is the speed of the rocket after a burn time of 145.0 s?
How did you find 4.5% is burned in 155 sec? Pls.
Thank you very much
because they ask you for half of the time,
so in your case in 145 it gets burned 5% in 145 seconds